Re: Do you know the reason for increased max latency due to xlog scaling?

Hi,

On 2014-02-18 00:43:54 +0900, MauMau wrote:
> Please let me ask you about your performance data on the page:
> 
> http://hlinnaka.iki.fi/xloginsert-scaling/padding/
> 
> I'm worried about the big increase in max latency.  Do you know the cause?
> More frequent checkpoints caused by increased WAL volume thanks to enhanced
> performance?

I don't see much evidence of increased latency there? You can't really
compare the latency when the throughput is significantly different.

> Although I'm not sure this is related to what I'm asking, the following code
> fragment in WALInsertSlotAcquireOne() catched my eyes.  Shouldn't the if
> condition be "slotno == -1" instead of "!="?  I thought this part wants to
> make inserters to use another slot on the next insertion, when they fail to
> acquire the slot immediately.  Inserters pass slotno == -1.  I'm sorry if I
> misunderstood the code.

I think you're right.

Greetings,

Andres Freund

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